1. Field of the Invention
This invention relates in general to vibration isolators and, in particular, to wire rope vibration isolators. More specifically, but without restriction to the particular embodiment hereinafter described in accordance with the best mode of practice, this invention relates to wire rope vibration isolator employing a crimp bar to secure the wire rope therein.
2. Discussion of the Related Art
Numerous mechanical systems require energy absorption devices for dissipating the kinetic energy of a component element in the system. Such mechanical systems include, for example, shipping cases, skids and containers, shipboard electronics and navigational equipment, pumps, generators and compressors, chemical processing equipment, avionics, and various other such industrial systems. Shock and vibration affect the performance of all types of mechanical and electrical equipment contained in these industrial systems. If such shock and vibration are left uncontrolled, they can cause premature equipment failure and costly downtime.
Many energy absorption devices have been proposed for use in industrial applications where control or damping of shock and vibration are required. One class of such energy absorption devices includes shock absorbers. The typical shock absorber is provided with a sealed outer cylinder, an internal shock tube, a piston having a head portion and a rod portion for engaging the moving system component, and an accumulator for collecting fluid from the interior of the shock tube when the piston head moves into the tube. The shock absorber also includes an orifice area that allows passage of fluid from the shock tube to the accumulator as the means for dissipating the energy received by the piston rod. A system of check valves and return passageways is also commonly provided to allow repeated circulation of fluid between the shock tube and the accumulator. The structure of this type of energy absorption device also requires various fluid seals to prevent leakage. The shock absorbers in class of energy absorption devices have many useful industrial applications. This type of shock absorber is mechanically complex and is ideally employed within a restricted temperature range.
An alternative class of energy absorption devices includes wire rope vibration isolators. This type of device does not include any moving parts, circulating fluid, or fluid seals. The wire rope isolator is thus ideally suited for extreme temperature applications. Such wire rope isolators typically include a coil of rope wire clamped between a pair of retainer blocks. The retainer blocks are secured against each other by a series of screws provided along the retainer blocks.
The art of wire rope vibration isolators has been contributed to by a number of proposed devices including the metal cable absorber illustrated in U.S. Pat. No. 3,596,865 issued to C. Camossi, the isolator apparatus shown in U.S. Pat. No. 4,783,038 to C. L. Gilbert et al., and the vibration and shock absorber device discussed in U.S. Pat. No. 5,062,507 issued to A. Roche. All of these devices employ threaded fasteners to clamp two retainer blocks against each other with wire rope coils secured between the blocks. While this type of isolator has advantages, the machining of the threaded hole and complicated assembly require substantial time. In addition there is the possibility that the threaded fasteners become loose during the service life of the device. The vibration isolator proposed by R. E. Belfield et al. in U.S. Pat. No. 4,190,227 employs a method whereby the wire cable coils are molded in retainer block which is formed from a thermoplastic material such as polyvinyl chloride or polystyrene. While this type of device avoids costly machining associated with other types of prior wire rope isolators, it may fail under extremely heavy loads or temperatures. The manufacture of the molded retainer block also requires costly molds and complicated melting and curing operations. A structural disadvantage of the molded retainer block is that the bonded interface between the thermoplastic material and wire cable may fail due to cyclic fatigue.